Marseillevirus is a giant virus that was isolated in 2007 by culturing water collected from a cooling tower in Paris, France, on Acanthamoeba polyphaga. Since then, five other marseilleviruses have been detected in environmental or human samples. The genomes of two of the six marseilleviruses have been described in detail. We describe herein the genome of Cannes 8 virus, a new member of the proposed family "Marseilleviridae." Cannes 8 virus was isolated from water collected from a cooling tower in Cannes in southeastern France. Its genome is a circular double-stranded DNA molecule with 374,041 base pairs, larger than the Marseillevirus and Lausannevirus genomes. This genome harbors 484 open reading frames predicted to encode proteins with sizes ranging from 50 to 1,537 amino acids, among which 380 (79 %) and 272 (56 %) are bona fide orthologs of Marseillevirus and Lausannevirus proteins, respectively. In addition, 407 and 336 predicted proteins have significant hits against Marseillevirus and Lausannevirus proteins, respectively, and 294 proteins are shared by all three marseilleviruses. The Cannes 8 virus genome has a high level of collinearity (for 96 % of orthologs) with the Marseillevirus genome. About two-thirds of the Cannes 8 virus gene repertoire is composed of family ORFans. The description and annotation of the genomes of new marseilleviruses that will undoubtedly be recovered from environmental or clinical samples will be helpful to increase our knowledge of the pan-genome of the family "Marseilleviridae.".